Cookie

A cookie is a text file that is stored in the memory of the web browser by the server when a user visits a website (it can also be stored by a third-party server that is allowed to do so - ad network, web analytics service...). Cookies make it possible to gather and store data about users’ browsing behaviour, which can later be reused during these users’ subsequent visits (user log ins, for instance).

As cookies are stored at the browser level, they identify users through a given browser on a given device, which creates bias. Since the ultimate goal is to count the number of users – and not the number of browsers -, the challenge is to reconcile users’ cross-browser and cross-device journeys, and thus to deduplicate conversions.